1. Field of the Invention
This invention relates to the field of automation of process control. In particular, this invention relates to an apparatus for achieving real time yield control of the number and types of usable pieces of desired sizes and shapes obtained from raw material.
2. Description of the Prior Art
Maximizing the yield of usable pieces from raw material has been of interest in industrial production for many years. Factors to be considered include the position and orientation of the pattern of pieces on the raw material, shapes and ratios of types of usable pieces to be produced, and the size, shape and nature of the raw material. The situation becomes particularly complex when natural products are being used, as they are likely to be of irregular shape and are more likely to contain flaws than a manufactured product. Each piece of a natural raw material calls for a separate yield calculation and a different arrangement and assortment of usable pieces is likely to be necessary to maximize yield.
Calculating the yield involves determining the area of the raw material, measuring the area of usable pieces produced and expressing the latter as a percentage of the former. If either the raw material or the usable pieces produced are irregular in shape, the calculations are complex and are best accomplished by a computer.
Current methods of yield calculation commonly require the use of a keypad or keyboard for numerical entry. This procedure introduces a number of difficulties. It is time-consuming and introduces the possibility of data entry error. In addition, a yield value alone does not guide a production worker to increase or decrease production of particular pieces.
Accordingly, a need remains for a process in which the yield of pieces can be determined without any additional processing time, without a delay in obtaining results, with a reduced need for separate data entry steps, and with the capability of providing feedback to the process operator. This invention determines yield in real time, provides instantaneous results to an operator or supervisor, and utilizes automated data entry capabilities.
In order to meet this need, the present invention is an apparatus and method for achieving real time yield control of the number and types of usable pieces of desired sizes and shapes obtained from raw material. The raw material is laid out and conveyed to a cutting station. Dies in the shapes of desired pieces are placed on the raw material. Areas of raw material encompassed by the dies are calculated and subtracted from the total usable area of raw material to determine the yield. The yield is compared to a designated preset threshold value determined for each job. The pieces are then cut from the raw material.